Evas textblock: Replace the rbtree index with a fixed ptr array.

Evas textblock: Replace the rbtree index with a fixed ptr array.

This possibly doesn't scale as good but it's good enough for everything I've
tried. It's a lot easier to maintain comparing to the rbtree, and takes a
lot less memory. Next step is probably changing the array size according
to the actual content of the textblock.

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/evas@63474 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33